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Need hints for manual focusing the Samyang 12mm
#1
Dear all,

 

a few days ago I got my Samyang 12mm NCS for the e-mount. I couldn't test it until today: unfortunately this week I had an emergency at home, my father got hospitalised in emergency sunday night and in my family we spent two sleepless nights (now he's at home in convalescence and things are going well).

 

Today I had a few minutes for a test en plein air. Clearly I've still to recover the stress of the past days, because I did a mistake in manual focusing (computing the hyperfocal distance at ƒ/2): all tests at ƒ/2 are a disaster, while those at ƒ/5.6 are very poor. I have some suspects that the lens might be a lemon, but there are high chances it was mostly my fault. Actually, thinking it over, the markings on the focus rings are quite disappointing: they go up to 1m (3ft) and then there's the infinity one. Nothing in the middle. Too bad, because there is room for one further marking in the middle.

 

Now, the hyperfocal distances for ƒ/2 and ƒ/5.6 are 3.6m and 1.3m. Do you have some hint on how to set them? Also, I've read that Samyang focusing distance markings are often inaccurate, and this worries me: for ƒ/5.6 I correctly calculated the hyperfocal and put the ring slightly beyond 1m, but if the ring is really inaccurate it could have been the problem.

 

Thanks.

 

stoppingdown.net

 

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm Æ’/5-6.3 DG OS HSM Contemporary, Samyang 12mm Æ’/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm Æ’/2.8, Samyang 8mm Æ’/3.5 fish-eye II | Zenit Helios 44-2 58mm Æ’/2 
Plus some legacy Nikkor lenses.
#2
I recommend focusing to infinity and then pulling back until you get a sharp image where you want it instead of messing with hyperfocal nonsense.  Truth is in real lenses DoF calculators are wrong anyway, since the airy disk doesn't match a simple diffraction pattern. 

#3
Do as Scythels says, and if you have live view, which you must as it's for mirrorless, try to magnify the image to see focus better. But it's always hard as everything can look in focus on a small screen. I used this with the X-T1 for a few months until I sold both (will buy the lens for NX mount soon), but it was OK on that camera. I preferred looking into the EVF with the view magnified if there was little to see peaking on (like stars) simply cause the EVF has more resolution and then more detail than the screen.

#4
I don't know if they have got better, but I have an earlier copy of their 8mm fisheye for DSLRs and the focus scale on that wasn't even close. I wasn't alone on that. Other people realised you can disconnect the outer part of the focus ring by undoing some screws, and then align it correctly before fixing it once more. I did that to mine and it is close enough now. See it as like focus micro-adjust for manual lenses Smile Again, I don't know if this might affect their more recent lenses, but certainly you can test it to see e.g. put a target exactly 1m from the focal plane, and see where you have to turn it for best focus.

Otherwise... I'd probably use magnified live view to nail focus on the primary subjects. If there isn't time for that, stop down and don't worry about it.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.
#5
For me the hyperfocal technique works with the 8mm, but the DoF is so large with that lens at ƒ/8 that it might work in spite of large errors in the scale.

 

I'll retry as you suggested. I think I have to use the NEX-6, because I don't feel at ease in manual focusing with the inferior EVF of the A6000.

stoppingdown.net

 

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm Æ’/5-6.3 DG OS HSM Contemporary, Samyang 12mm Æ’/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm Æ’/2.8, Samyang 8mm Æ’/3.5 fish-eye II | Zenit Helios 44-2 58mm Æ’/2 
Plus some legacy Nikkor lenses.
#6
I've seen lots of posts about infinity focus on Samyang lenses being poorly calibrated, here's a Utube video showing how to adjust the focus ring,  well I didn't in fact watch it, however it shows how th roll back the rubber to access the screws so you can adjust the it, I guess you use live view to focus on infinity and then undo the screws to set the ring.

  Unfortunately, it's in Spanish and is subtitled in French but you'll get the picture if you pardon the pun! It's of the Samyang 14mm but the principle's the same I think!

 

https://www.youtube.com/watch?v=gtt9bcJD...e=youtu.be

 

 

 My 8mm fish eye was OK!

Dave's clichés
#7
Thanks.

 

I can read french (in any case I see subtitles are in english too). But the 12mm doesn't have a rubber band for the focusing ring. In any case, I won't touch it now that it's brand new and still in warranty, until I find it's optically ok.

stoppingdown.net

 

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm Æ’/5-6.3 DG OS HSM Contemporary, Samyang 12mm Æ’/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm Æ’/2.8, Samyang 8mm Æ’/3.5 fish-eye II | Zenit Helios 44-2 58mm Æ’/2 
Plus some legacy Nikkor lenses.
#8
I couldn't find anything on the 12mm Samyang unfortunately!

 

 

 

Good luck!

Dave's clichés
#9
Iv'e had two capies of the Sammy 14 (one in Canon mount and one in SonyE) and one of the 351.4; and in both cases the focussing scale was MEANINGLESS. Massively out of calibration.

I think I see how to calibrate the 14, but I haven't bothered. But if you are really set on hyperlocal calculations then you'll have to. You can set up targets at various distances to the film plane. I imagine (but am not sure) that the *relative* distances are right, once you have infinity calibrated. Though I'm not at all sure - my impression with the 14 was that the error was different at different distances.

 

Optically great lenses though, the hassle is well worth it at the price. I sold my canon 14II for two grand, bought the sammy and pocketed $1700. With a distortion profile for when it matters the Sammy  is easily as good.

 

Thing about hyperfocal work, though, is that there is a trade off between getting infinity and some nearby point sort-of-sharp, and getting the thing that really care about tack sharp. I reckon just focus the thing in the EVF.

 

 

#10
Quote:I don't know if they have got better, but I have an earlier copy of their 8mm fisheye for DSLRs and the focus scale on that wasn't even close. I wasn't alone on that. Other people realised you can disconnect the outer part of the focus ring by undoing some screws, and then align it correctly before fixing it once more. I did that to mine and it is close enough now. See it as like focus micro-adjust for manual lenses Smile Again, I don't know if this might affect their more recent lenses, but certainly you can test it to see e.g. put a target exactly 1m from the focal plane, and see where you have to turn it for best focus.


Otherwise... I'd probably use magnified live view to nail focus on the primary subjects. If there isn't time for that, stop down and don't worry about it.
They had this problem on the 14mm f/2.8 as well, I was lucky however, and it was spot on Tongue
  


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